Solve for $x$ and $y$ using substitution. ${x-2y = 10}$ ${y = x-7}$
Solution: Since $y$ has already been solved for, substitute $x-7$ for $y$ in the first equation. ${x - 2}{(x-7)}{= 10}$ Simplify and solve for $x$ $x-2x + 14 = 10$ $-x+14 = 10$ $-x+14{-14} = 10{-14}$ $-x = -4$ $\dfrac{-x}{{-1}} = \dfrac{-4}{{-1}}$ ${x = 4}$ Now that you know ${x = 4}$ , plug it back into $\thinspace {y = x-7}\thinspace$ to find $y$ ${y = }{(4)}{ - 7}$ $y = -3$ You can also plug ${x = 4}$ into $\thinspace {x-2y = 10}\thinspace$ and get the same answer for $y$ : ${(4)}{ - 2y = 10}$ ${y = -3}$